Xantia Hydractive Cork-Screwing...

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aerodynamica
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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

Thanks, that's brilliant - I will definatey do those checks and inspect the small spring before condemning the block. I vaguely recall seeing that thread once before.

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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

I've now had a look at the front electro valve. Fortunately it's relatively easy to remove from above although very tight.

So i removed the small spring and checked the length - it's a little over 9mm in length. I stretched it over a few times and checked the length each time and it is now 11.4 mm. I didn't want to go mad this time. I looked at the needle valve and cleaned it but cannot tell if it's worn at all. Or if the corresponding seat is worn. Reassembled with new locktite and primed up and running. No leaks so far. Bit of citaerobics and a few jabs of the accelerator to make the electro valve shuttle under pressure. Just to get everything settled back in.

Not driven yet but soft mode is there as is hard. Initial assessments of the regulator tick time isn't looking great - seems to still be quite fast although it might be very slightly improved.

I have a drive home later so will see what happens. Thanks for the help so far.

Sorry to hijack this thread!

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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

I've driven back home and found the front now rides a lot better.

The tick times however are still fast at 16 seconds in soft mode.

I used the modified master switch I fitted to override the ecu power and switch off the hydractive to switch it to hard mode while it's running and now i notice the tick time in hard mode is immediately up. I was getting between 35 to over a minute (it seemed to be increasing each time) so after 5 minutes i switched the ecu back on and immediately it returned to fast tick times of 16 seconds although strangely, this too improved to 21 seconds over the next few minutes timing it.

All I've done is stretch that little spring a bit. I might revisit this but will be after the chevrons rally now.
Last edited by aerodynamica on 09 Sep 2019, 23:23, edited 1 time in total.

aerodynamica
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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

can see the little spring measurement before and the larger spring too. Two pictures show how the small spring sits in the needle valve before and after.

Strangely reminiscent of a paint gun valve.
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xantia_v6
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Re: Xantia Hydractive Cork-Screwing...

Post by xantia_v6 »

Maybe the rear electrovalve also needs tickling?

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white exec
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Re: Xantia Hydractive Cork-Screwing...

Post by white exec »

That was my thought, too.
Did you ever check the quantity of leak-back from each of the EVs? The volume of leak should be tiny, and only there when the valve actually switches.
Easy enough to attach a length of clear pipe to the EV return snout.

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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

Good shout. I didn't suspect the rear one because it's the front that sinks fast and also has unsatisfactory ride in soft mode. The rear is wonderfully soft with a taut firm mode. I'll do the leak check soon

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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

Now I think of it I can easily check the front leakback rate because of the relatively easy access. If it's still gushing through then that might be the cause... however if it's good then that would suggest another internal leak source such as the rear unit.

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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

Hmm checked the front EV leakback and apart from an initial small flow, there was absolutely none. A mere pulse in the clear pipe when I made the EV activate.. all the while the tick time was about 20 sec. After switching off the fruit sinks in about 10 min, rear stays up for over an hour.

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Re: Xantia Hydractive Cork-Screwing...

Post by xantia_v6 »

It looks like your rear electrovalve needs attention, for the early HA2 valves (like yours), the internal leakage comes from the main high pressure supply, not the suspension.

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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

But why does the rear suspension still work so well? very soft in soft mode and properly firm in firm mode just like the front. And I'd have thought the rear suspension would be the one to sink fastest if that's where the leakage is.

Only other thought on it however, is that the rear struts and spheres etc contain a lower pressure of LHM in the most common situations (fuel tank on average 1/2 full, no rear passengers) and of course the mechanical biases of the system that render the rear pressure lower anyway. This lower pressure might have a smaller visible effect on a leaking EV at the rear than if it is the front one.

I'll investigate the rear one in due course. Certainly the front suspension is noticeably better after stretching that little spring.

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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

Mini contribution to this: After I got a new set of tyres a few weeks back I noticed no improvement to the strance 'wobbliness' at times even after the work I'd done recently to revamp the Hydractive Electro Valves.

Today however, I removed the 15mm wheel hub spacers from the rear wheels and the 3mm spacers fromt the front. It was like traveling back in time..... to when the car used to work properly.

25 mile journey later I'm convinced that the whole problem was caused by the wrong offset on the rear wheels. I think I had underestimated the effect of offset on the trailing arm arrangement. I thought trailing arms would be practically immune to badly chosen offset but there must be some aspect of, maybe, the fixed camber or something. I also think the wider rear track (although still 6mm narrower than the front) was giving too much of a mechanical advantage diagonally.

Anyway, the spacers shall now remain off!

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white exec
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Re: Xantia Hydractive Cork-Screwing...

Post by white exec »

Now you mention the altered offset, I recall that Xantia, XM and ZX all have "passive rear wheel steering", which I guess would be affected by altering the geometry of the arrangement.

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Re: Xantia Hydractive Cork-Screwing...

Post by aerodynamica »

Yes Chris, and for a white I was wondering how the passive rear steering stood up after all these years. I wondered if the flex mounts responsible for the set up might be failing. No real way to test it though. Anyway, honestly it is still feeling better after removing the spacers and looking at the car; to me it looks fine without them (I don't know what I was thinking fitting them ...)